Reverse osmosis as a potential technique to improve antioxidant properties of fruit juices used for functional beverages.

Reverse osmosis (RO) as a potential technique to improve the antioxidant properties of cranberry, blueberry and apple juices was evaluated for the formulation of a functional beverage. The effects of temperature (20-40 °C) and trans-membrane pressure (25-35 bars) on physico-chemical and antioxidant properties of fruit juices were evaluated to optimize the operating parameters for each fruit juice. There was no significant effect on any quality parameters of fruit juices under studied operating parameters of RO. However, total soluble solid, total acidity and colour (a(∗)) of the concentrated juices increased in proportion to their volumetric concentrations. Antioxidant capacity measured by FRAP assay of concentrated apple, blueberry and cranberry juice was increased by 40%, 34%, and 30%, respectively. LDL oxidation inhibition by concentrated blueberry and cranberry juice was increased up to 41% and 45%, respectively. The results suggest that RO can be used for enhancing the health promoting properties of fruit juices.